The present invention relates to manufacturer of polymer syringes for clinical use with patients.
Medical professionals are aware of the hazards of injury and death to patients from air bubbles in the blood. An air embolism, also called a a gas embolism, is a blockage of an artery or vein by an air bubble. Air can be introduced into the blood vessels during surgery or traumatic accidents. One example of an air embolism is the xe2x80x9cbendsxe2x80x9d, a common hazard of underwater diving while breathing compressed air. Another type of traumatic embolization occurs when lung tissue is ruptured; bubbles of air pass from the alveoli (air sacs) of the lungs into nearby capillaries and veins. The air bubbles are then carried into the heart, where, if trapped, they can cause myocardial infarction, the destruction of tissue in the heart muscle; usually, however, the air rises to the brain. The consequent blockage of vessels carrying blood to the brain starves this tissue of its vital blood supply. Nervous tissue becomes irreversibly damaged after about five minutes of oxygen and nutritional starvation; convulsions, unconsciousness, respiratory difficulties, and death may ensue.
In view of the hazards of air embolisms, great care is taken to avoid introduction of air into the blood stream during surgical procedures. For instance, intravenous (IV) catheters are arranged so that air will not be entrained into the vein during use. Injection of medicines and inoculations by needle are performed after air is expelled from the syringe. These measures minimize inadvertent injection of air into the patient. Even when air is accidentally injected, generally no harm occurs due to the small amount of air involved and the site of the injection. The patient""s body is often capable of absorbing the gas before it reaches a critical part of the body such as the heart or brain. However, the presence of air in a syringe or catheter is still a cause for apprehension.
Injection of contrast medium into a vein or artery is a specific example of a surgical procedure wherein great care is exercised in avoiding the introduction of air bubbles. As an example, angiography, also called arteriography, is the diagnostic imaging of arteries and veins, using radiological modalities such as x-ray, ultrasonics, and magnetic resonance imaging (MRI). To differentiate circulatory structures from the surrounding organs and to perform dynamic studies of circulation flow, often contrast media is injected into vessels. The contrast media is opaque to the imaging modality (e.g., x-ray) or otherwise enhances the return (e.g., MRI). Powered injection of contrast medium during angiography is often desirable. A power injector provides a predictable rate of flow, generates sufficient force to inject viscous contrast media, and allows medical personnel to be further removed from the imaging system.
Avoiding introduction of air to the blood vessel is a key part of the design and operating procedures for power injectors. First, these angiographic procedures generally inject a relatively large quantity of contrast media at a significant pressure, thus compressing any air bubbles during injection. The air bubbles expand after injection into a large vessel, and thereafter can quickly reach critical circulatory structures in the body. Consequently, the syringes are filled and air removed prior to preparing the patient for catheterization. The plunger end of the syringe is elevated during injection so that any remaining air bubbles tend to stay in the syringe during injection. Keeping the air bubbles in the syringe is assisted by the rate of flow within the syringe. Bubbles that form on interior surfaces are subject to low rates of flow and thus tend to remain until mechanically wiped by the plunger, accumulating at the rear of the syringe during the procedure.
Thus, while the design and procedures minimize the risk of air embolisms, there is an inconvenience involved in preparing the injector. Not only do the medical professionals have to spend time removing air bubbles as a good clinical practice, often small amounts of remaining air bubbles that pose no risk are removed to avoid apprehension by the patient. The additional time required to remove air bubbles slows the process of imaging and increases the staffing required to perform the imaging. Since the equipment for diagnostic imaging is expensive, even small delays to the process decrease the usage of the diagnostic imaging facility, thus increasing the cost per patient to amortize the fixed costs for equipment and the facility.
Therefore, a significant need exists for a syringe for injecting fluids into the body that has a reduced tendency to accumulate air bubbles.
The present invention addresses these and other problems in the art with a syringe and a method of producing a syringe wherein the interior surface of the syringe is treated with a hydrophilic surface treatment to reduce attachment of air bubbles when injecting a water-based fluid. Thereby the time required to prepare the syringe is reduced and patient apprehension reduced.
The above and other objects and advantages of the present invention shall be made apparent from the accompanying drawings and the description thereof.